IgE antibodies against midge and moth found in Japanese asthmatic subjects and comparison of allergenicity between these insects.

The specific IgE antibodies to moth (Bombyx mori) and midge (Chironomus yoshimatsui) were measured by the Pharmacia CAP system in 51 house-dust-mite-sensitive asthma patients. None of these patients had definite histories of exposure to these insects or apparent evidence of insect-induced asthma symptoms. The RAST-inhibition assay was performed to investigate cross-allergenicity between these two insects. Furthermore, IgE immunoblotting was done to study the IgE-binding components in moth and midge extracts. Thirty (59%) of these patients showed positive IgE antibodies to moth, while 25 (49%) showed positive IgE antibodies to midge. Those frequencies of positivity were similar to that for Japanese cedar pollen, which is well known to cause allergy. A significant correlation (r = 0.863) was observed between IgE antibody titers of these two insects. The results from the RAST-inhibition assay indicated cross-allergenicity between these insects and also the existence of species-specific allergens. Fifteen IgE-binding components in moth extract were observed. The most frequent IgE-binding protein was the 79-kDa (84.2%), followed by the 72-kDa (78.9%), the 82-kDa (57.9%), and the 76-kDa (57.9%) proteins. Those were considered to be major allergens in moth. Twenty-four IgE-binding components in midge extract were observed. However, no IgE-binding protein to which over 50% of patient sera reacted was observed. These results suggest that these two insects may be considered to bear important allergens and that there is cross-allergenicity between these insects as well as species-specific allergens.